The Federal Aviation Administration (FAA), guardian of air safety, depends on more than 13,000 private companies and individuals to perform a variety of safety-related tasks: testing applicants for pilot's licenses, signing off on the installation of complex airline equipment, and the like. As in the private sector, it's a money saver.

But a new report from Congress' Government Accountability Office (GAO) finds gaps in the system, with dangerous implications.

The report was requested after USA TODAY exposed laxities that may have contributed to the 1998 crash of a Swissair jumbo jet that caught fire and plunged into the Atlantic off Canada, killing all 229 aboard.

Canadian safety officials couldn't pinpoint the location of the short-circuit that started the fire, but the plane's entertainment system was a primary suspect. The installation of that system was overseen by a company that the FAA had repeatedly criticized, even briefly lifting its authorization to do FAA safety work.

Problems at the company were plentiful. On one Swissair plane, the inspection firm certified the entertainment system before it was functional. And prior to the Swissair job, the FAA found problems in 11 other safety certifications that the company had issued.

Now, the GAO has found numerous other weaknesses in the outsourcing system, including:

•Lax oversight. During the past seven years, the FAA's Washington headquarters has evaluated only six of the 18 programs that use outsourcing. Even when red flags have appeared, the FAA hasn't always followed up. For instance, in 1999, the FAA found that inspection firms in the Orlando area had signed off fraudulently on test results for hundreds of airline mechanics seeking certificates to work on planes. The FAA was forced to retest them. Yet, the mechanics program, which includes 385 private examiners, has not been evaluated since then, according to the GAO.

•No penalties. Inactive, unqualified or poorly performing firms are not identified and removed expeditiously. FAA field offices told the GAO that the firing process is too time-consuming. In one case, an FAA engineer said it took two to three years.

•Overworked inspectors. Some FAA inspectors had too great a workload to conduct required surveillance.

The FAA points to the GAO's conclusion that there are no "systematic safety problems" in the agency's oversight.

That, however, sidesteps the real danger: The FAA's spotty oversight leaves it blind to potential problems. Its lack of follow-up leaves questionable operators in place to approve pilots, mechanics and complex aircraft alterations, such as Swissair's system.

Crashes are rare, and millions of flights each year operate safely under the system. But the FAA shouldn't need another Swissair to know that without quality control, its outsourcing system is flying blind.